Processing of hydrocarbons



Patented Nov. 27, @945 UNITED STATES 'ilATiENT 50F Fl CE PROCESSING'OFHYDROCARBONS Eric .William Musther Fawcettzand :Eric Sylvester Narracott, Sunbury on :Thames, England, as-

signors-to Anglo-IranianO il Company Limited, London, :England, aBritish joint-stock com- 'No Drawing. Application May 21, 142,'Serial-No. 4 43;980. ImGreat BritainsAipril '7, 1941 .BJClaimst (GLEN-683.5)

This invention relates to the con-version wholly or in part of norma1aliphatic hydrocarbons -=such as n-butane and n-pentane or n-iateriialscontaining substantial proportions of such hydrocarbons, 5 into thecorrespondmg branched chain hydrocarbons such as isobutane andisopentane or into mixtures containing substantial proportions ofbranched chain hydrocarbonsof lower molecular weight, for example thecon-versionof n-pentanelto isobutane.

In such processes it is customary to employ.

as contact catalyst certain anhydrous metallic halides of which aluminumchloride is typical, while in order to increase -the activity of thealuminium halide it is usually found desirable to employ an -activatingagent such as hydrogen chlorideor water.

The invention has among its objects to increase substantially theactivity of the catalyst and to accelerate the conversion of normal tobranched chain hydrocarbons.

According to the invention, an aluminium halide is used as catalystpreferably in conjunction with a hydrogen halide, but in the presencealso of a proportion of a volatile sulphur compound of the type where R1and R2 are hydrogen or alkyl radicals, and R1 and R2 may be identicalhydrogen or alkyl radicals or respectively hydrogen and alkyl radicals.A typical example of such sulphur compounds is ethyl mercaptan -C2H5(H)S. The proportion of the sulphur compound to be used corresponds to anupper limit of 5% of sulphur by weight of the hydrocarbon raw material.

The process may be carried out in the liquid or vapour phase, and eitherin batch or continuous operation.

In a preferred mode of operation, a continuous stream of a mixture ofthe hydrocarbon raw material in vapour phase, a hydrogen halide,advantageously hydrogen chloride, and the sulphur compound are passedthrough a reaction vessel containing the aluminium halide catalyst ingranular or other suitable form, such for example as in admixture withor supported on a porous carrier, the reaction vessel being maintainedat a determined temperature and pressure. The product leaving thereaction vessel and containing substantial amounts of branched chainhydrocarbons may be fractionated, for example by distillation, in orderto separate partially or completely the normal rand=1branched chainhydrocarbons. The normal hydrocarbons may be recycled to the same "orother reaction vessel. 7

'thydrogen nance and/or the vcntne :sul-

phur compound may also be lrecovered an'd reployed and if d'esired,the=catalytic matenials-may be used together with waten being :a knownoatalyst 'activator, instead of "or together with a hydrogen hal-ide. aI v a The enhancedea'ctivity of the oatalyst -under'the conditionshereinbefore described is demonstrated in the following experiment.

ExampZe.n-Butane containing 17.1% by volume of hydrogen chloride waspassed at a rate of 13.6 gas volumes per volume of catalyst per hourthrough a reaction vessel containing granular aluminium chloride, andmaintained at 123 C. and at atmospheric pressure. The gas leaving thereaction vessel was found to contain 13.8% isobutane.

A n-butane feed-stock containing .4% by weight of ethyl mercaptan andcontaining 17.1% by volume of hydrogen chloride was then passed at thesame rate through the same reaction vessel containing the same sample ofcatalyst and maintained at 123 C. and at atmospheric pressure. Samplesof the issuing gases were taken at frequent intervals, and analysed foriso-butane content; the results are tabulated below:

Thus by the use of the ethyl mercaptan as a catalyst activator under theconditions referred to, the reaction rate is about 2.5 times greaterthan that observed under equivalent conditions in its absence.

We claim:

1. A process which comprises isomerizing at least one normal paraflincontaining at least four carbon atoms per molecule in the vapor phase ata temperature between 50 and 300 C. and 5 superatmospheric temperaturewhile in contact with an aluminum halide and in the substantialcontinuous presence of a compound of the type I RSI-I wherein R isselected from the group conslsting of alkyl and hydrogen.

2. A process which comprises. isomerizing at least one normal parafllncontaining at least four carbon atoms per molecule in the vapor phase ata temperature between 50 and 300 C; and superatmospheric temperaturewhile in contact with an aluminum halide and in the substantial con.-

tinuous presence of a compound of thetypeRSH wherein R is selected fromthe group consisting of alkyl and hydrogen and wherein the reaction isfurther promoted with the aid of a hydrogen halide.

3. A process which comprises, isomerizing at least one normal paraflincontaining at least four carbon atoms per molecule in the vapor phase atr a temperature between 50 and 300 C. and superatmospheric temperaturewhile in contact with aluminum chloride and in the substantialcontinuous presence of a compound of the type RSH wherein R is selectedfrom the group consisting of alkyl and hydrogen.

4. A process which comprises isomerizing at least one normal paraflincontaining at least four carbon atoms per molecule in the vapor phase ata temperature between 50 and 300 C. and super-;;;

atmospheric temperature while in contact with aluminum chloride and inthe substantial conleast one normal paraflin containing at least fourcarbon atoms per molecule in the vapor phase at a temperature betweenand 300 C. and superatmospheric temperature while in contact withaluminum chloride and in the presence of a lower alkyl mercaptan andwherein the reaction is further promoted with the aid of hydrogenchloride. V A

7. A process as in claim 5 wherein thefeed stock comprises essentiallynormal butane.

8. Aprocess as in claim fi whereln thefeed stock comprises essentiallynormal pentane.

9. A process which comprises isomerizing normal butane at a temperaturebetween about 50 C. and about 300 C. in the vapor phase, in the presenceof aluminum chloride and promotional amounts of hydrogen chloride,wherein the reaction is carried out in the presence of between about 0.4and about 5 .weight per cent of ethyl mercaptan based on the normalbutane Ieed.

ERIC WILLIAM MUSTHER FAWQE'IT. ERIC SYLVESTER NARRACO'IT.

